Goga Bai, 30, from Rajasthan in northern India, gave birth to her son via caesarean section on Thursday 1 October at Shri Ganganagar district hospital.
Dr Anamika Agarwal, one of the four doctors who delivered the child, said the baby's size was a "surprise" to both Goga Bai and her husband Ravinda Kumar, 28.
She said: "The baby and the mum are in sound health and doing okay.
"He is definitely the heaviest baby in the country. The normal weight of a newborn baby in India is 2.5 to 3.5kg [5 to 7lb].
"The baby initially had problems in breathing but now is doing okay. He is under constant observation."
Dr Agarwal also suggested that the baby's weight may be connected to his mother's diabetes.
"Gogi Bai is diabetic and weighs around 100 kg (220 lbs)," Dr Agarwal said.
"In cases where the mother is obese and diabetic, there is considerable risk of child being overweight too.
"Though no congenital anomaly has been detected in the child, we are keeping both him and his mother under observation and would discharge them after a week."
According to Guinness World Records, the heaviest baby ever born to a healthy mother was a boy weighing 10.2 kg (22lb 8oz) in Italy in September 1955.